Electrically-operated electric switch



Feb. 16 1926.

G. A. BURNHAM ELEGTRICALLY OPERATEP ELECTRIC SWITCH Filed Sept. 9, 1921 v 2 Sheets-Sheet 1 g w E N;

' I ow Feb. 16 1926. 1,573,674

, G. A. BURNHAM ELECTRICALLY OPERATED ELECTRIC SWIZNZH Filed 12.

Hesiiaiiny Weiaf.

MGM

Q /MM Patented Feb. 16 1926.

UNITE!) STATES IJlEll'TS, TO CONDIT ELEGTTJIGAL FIASSACHUSET'JTS, A CGRPOBA v Application filed September of Massachusetts, have invented an .lmprovement in ElectriCally-Operated Electric Switches. off which the following is a specification.

This invention relates to oil immersed electric switches particularly adapted to be automatically controlled. as automatically opened and automatically closed.

In automatic sub-station work, the oil switches are opened and closed automatically through a relay system and without operation or supervision by an attendant.

The ability of an oil immersed switch to interrupt its circuit under load depends upon the maintenance of an effective head oil in the switch above the switch in mhers at the pointat which the circuit in ing arc is drawn. When an oil ii switch is interrupted under a severe load. oil may be expelled from the oil receptacle ot' the switch and the oil level wi hin the switch consequently may he reduced. lVhen the switch opens under severe load condtions, or opens repeatedly under less sev load conditions, such an amount of oil in" he thrown from the switch as to expose switch members and it the switch is an: opened, the next circuit interrupting may occur in air. or in the gaseous contents t the interior of the switch; or at least toe oil level within the switch may become so reduced that the arc may burst through the oil and into the res-expansion space above the oil in the switch. Under such condi tions of aliens serious explosions and fires may occur. Inasmuch as there is no attendant near the switch, the reduced and dance known and guarded against.

An object of this invention is to provide an oil immersed electric switch with means In, ierned by the oil level wit iin the switch to make known the oil level.

A further object of the invention is to pro vide an oil immersed electric switch with means governed by the oil level tl erein to control and govern the operation ot the switch and, specifically, to govern the control circuit for the switch and to render inoperative said circuit to operate the switch Q FF IE BY MESNE ASSIGN- EORATEON, BOSTON,

FATEtTF up; out these objects of the inve11- tiou. provide a float within the oil rece tuclc. or otherwise clisposed to be moved in response to changes in the level of oil in the receptacle. Said float is arranged to cvern the movable member of an auxiliary si ch which is adapted to be associated with the control circuit of the oil immersed switch. Said oil-level governed auxiliary switch so a anged that it will not govern the controlling circuit when the oil level in the switch is sutliciently high but, when the o l level within the switch descends to a predet niued low point, the auxiliary switch will to govern the control circuit 1 the operation of the switch or, .(3 opening; of the switch, until the in restored in the switch.

ohicct ou this invention is to oil-level governed auxiliary an attachment to existing oil further ohiect is to generally improve construction. operation and control of 0 sad electric switch.

is an elevation. of a three-pole clcctrically-controllcd oil-immersed electric odyinc; the invention.

ionel detail through a .iQ. f2 and illustrating; in

us here shown. three-pole switch has lreeu selected to illustrate the invention.

and the switch comprises the switch frame l0 three oil receptacles 11 removahly leper. r therefrom. Three sets of stationary swit h-members 19 are carried by said ame and are immersed in the oil in said cptaclcs a rd three movable switch memalso inunersed in the oil in said and connected with the operat mg mechanism 1%. Said switch is adapted to be operated by electrically controlled devices wherein is the closing coil and 16 is the trip coil associated with the switch operating mechanism 14:. The oil-level governed auxiliary svitch comprising a part of this invention is preferably supported removably from the switch frame 10, and preferably a separate auxiliary switch is associated with each oil receptacle. Said auxiliary switch may include the float 17 secured on the end of an arm 18 disposal within the oil receptacle 11. Said arm 18 may be pivotally carried by the bracket- 19 which is secured dependingly from the switch frame. Said float 17 is adapted to be partially immersed and float in the oil in said receptacle to rise and tall in accordance with variations in the oil level. An insulating block 20 may be secured to the top of the switch frame and may have the two stationary contact members 21 secured thereto. Said contact members are adapted to be included in an electric circuit arranged to govern the controlling circuit for the switch. A bridging member 22 is car 'ied adjustably on the upper end ot a rod and said rod is guided tor vertical movement in the insulating; blocl: O. Said rod extends below the switch trai'ne and may be provided with a forked end 2-1 between which the i at arm 18 may be disposed. A pin may be extended between the forks of said rod and through a slot 26 in the float arm whereby to connect said rod 23 and arm 18 loosely.

In the normal position of the oil level within the receptacle as shown in Fig. 2, the float adapted to support the bridging nien'iber 22 some distance above the contact 7 members 21 whereby the auxiliary switch will be unel'i'octivc in governing the controlling circuit for the oil switch. When. however, the oil level in the switch descends to some low position by reason of expulsion of oil from the switch when the circuit is opened under heavy load said float 17 will descend with the oil level and eventually move the bridging member 22 into contact with the contact members 21, as indicated in Fig. 3, and close the circuit associated therewith and govern the controlling circuit will hereinafter be set forth.

The particular form of mechanism connecting the float 17 with the bridging member 22 may be varied to fulfill different requirements.

Tn Fig. -l a modified form of mechanism is illustrated, and the bridging member .22 is secured to the upper end of a tubular member 23 which is slidably received in the insulating block 20. The float 17 is secured to a stem 18 and said stem is adjustably received within said tubular member 28 and secured thereto in adjusted position means of the set screw 27. \Vith this arrangement the float is connected directly to the bridging member and the distance between the float and bridging member may varied to provide for differences in positions of noimal oil level in different oil recept-acles.

The switch en'ibodying the invention is usually provided with an auxiliary switch governed by a movement of the main switch. As here shown, said latter auxiliary switch includes the movable switch member 30 which is adapted to biidge the set of contact members 31 when the main switch is closed and to bridge a second set of oppositely disposed contact members when the switch is opened, as is usual practice. The control circuit adap'ed automatically to control the opening and closing of the switch and be overned by the oil-level governed auxiliary switch is illustrated in Fig. (i.

The control circuit includes the overload relay 35 which is adapted to be energized upon a predetermined overload in the circuit controlled by the oil innnersed switch to operate to bridge its contact member 37. The bridging of the contact members 37 serves to energize the trip coil 16 from the auxiliary power circuit 38 through the contact members 31 and bridging members 30 of the auxiliary switch ot the main switch. hen the main switch opens, said bridging member 30 will be moved away from said contact members 31 thereby to open the trip coil circuit, and said bridging member 30 will be moved to bridge the contact member to condition the control circuit for the closing of the switch.

The control circuit is usually provided with means arranged automatically to control the closing of the switch and cause the switch to be closed successively a predetermined number of times separated by predetermined time intervals. and thereafter open the switch and lock it open. The switch closing means includes a definite time limit relay 39 and the notching relay 40. The bridging of the contact members 32 of the auxiliary switch when the main switch moves to open position, operates to close the circuit through the definite time limit relay 39, the notching relay 40, the contact members ll of the notching' relay 4 0, all in series, to the auxiliary power circuit 38. The definite time limit relay :59 is provided with a suitable retardation device as the dash pot 89 which serves to retard the action of the movable element of the relay for a predetermined period, whereby to permit the switch to remain open a predetermined period of time as, say thirty seconds, or thereabouts. At the expiration of the predetermined period of time, the bridging member 39 of said relay will be moved upward to bridge the contacts 39 and thereby close the circuit of a hesitating relay l2. Said hesitating relay 42 is of more or less common construction and when energized is arranged to bridge its contacts 43 and thereby close the circuit of the closing coil 15. Said coil operates to close the switch. and, in the movement of the switch mechanism to the closed position, the auxiliary switch member 31 will be moved from bridging po sition with the contacts 32 and shifted into contact with the contacts 31, thereby disabling the closing circuit and permitting the notching relay 420, the definite time limit 39 and the hesitating relay to reset anc conditioning the control circuit to govern the opening coil of the switch. The hesitating relay 42 is so arranged that, when energized, its circuit-controlling member will be moved immediately to close the circuit and will be held in circuit-closing position by suitable means, not necessarily shown, to permit the switch-closing mechanism sufficient time to operate and then will drop back and break the circuit controlled by it. The notching relay is of more or less common construction and is here diagrammatically shown. It may include tl e movable switch member s 0 which is pivoted on the shaft 40 and is arranged to be held either in a position to bridge the contact 4-1 or in an open position by the spring 40. A. notching disc 40 may be pivoted on said shaft s0 and the notches are arranged to be engaged successively by the latch 40 of the actuating coil410. A dash pot 40 and its spring 40 may function to return said notching disc 40 slowly from a moved position to its initial position.

hen the switch closing circuit including he time limit relay 39 and the notching relay is energized to close the switch, the latch 4-0 will be moved upwardly to rotate the disc by the space of a notch. If the switch is closed, and remains closed, the notched disc will return gradually to its position. If, however, the switch is tripped open with in a few seconds, the latch 40 will be moved upwardly by the coil d0 to advance the disc a second notch. If the switch is again tripped open, the disc will again be advanced by the space of another notch and in this last movement may move the pin 40 adjustably carried in it against said bridging arm 40 and cause it to separate from the contacts ll; and the spring 40 will hold said bridging member away from said contacts and thereby disable the circuit and the switch will consequently remain open until the notching relay is reset by a operative.

The oil-level governed auxiliary switch embodying my invention is included in a circuit l5 in which is included a relay 46. When the oil level in the switch descends to a dangerously low point, the contact members 21 of said switch are bridged by the bridging member 22 and said relay all) is energized and operates to move its bridging member l? away from bridging position with the contact members l8 in the auxiliary power circuit 38, which controls the control circuit. Consequently, the control circuit is disabled and will be inoperative to control the switch until the oil level in the switch is again restored.

If desired, some forn'i of alarm device, as the indicating lamp l9, may be included in said circuit to direct the attention of an attendant to the fact that the oil level in the switch is dangerously low and the control circuit is out of commission.

The control circuit may include the manually operable remote closing switch and opening switch 51 with the appropriate si nal devices as the lights and 53 and associated with the elements of the automatic controlling circuit in the usual maning a closing coil, and means governed by the il in said switch to control the level of peration of said closing coil.

3. An oil immersed electric switch having a closing coil and an opening coil, and means governed by the level of oil in said switch to control the operation of said coils on said switch.

i An oil immersed electric switch having operating means therefor and means associated with said operatin means and governed by the level of oil in th switch to prevent the operation of the switch when the oil leve therein is dangerously low.

An oil immersed electric switch having electrically-actuated means for operating it and means governed by the fluid level in said switch to control said operating means.

6. An oil immersed electric switch having automatic electrically-actuated operating means for it, an auxiliary switch arranged to control said operating means, and means govt ed by the oil level in said oil immersed switch to govern said auxiliary switch.

7. The co "lbllltlllOll of a receptacle adapted to contain a fluid. an electrical apparatus imme 'sed in the fluid, a control system for said apparatus, and means governed bv the fluid level in said receptacle to govern the operation of said control system.

8. An electric switch incluoing a switch frame, an oil receptacle, switch members immersed in the oil in said receptacle, a float reresponsive to variations in level of the oil in said receptacle, and an auxiliary switch arranged to be operated by said float when the oil level reaches a predctern'iined low position, and switch-operating means governed by said auxiliary switch.

In testimony whereof, I have signed my name to this specification.

GEORGE A. BURNHAM. 

